First Frost, Freeze for Upper Midwest, Great Lakes

By By Meghan Evans, meteorologist

September 22, 2012, 12:05:39 AM EDT

Some Midwesterners will wake up to the first frost and freeze of the season this week, while others around the northern Great Lakes may witness the first snow flakes of the season.

Drastically colder air is surging into the Midwest behind a cold front, allowing temperatures to plummet by 20-30 degrees.

Clear and calm conditions behind the front will allow for temperatures to drop near and below freezing across eastern portions of the Dakotas, Minnesota, northern Iowa and northwestern Wisconsin early Tuesday morning.

Fargo, N.D., Aberdeen, S.D., International Falls and Duluth, Minn., are among the cities and towns that will have their first frost or freeze of the season.

Any outdoor plants in pots should be brought inside, gardens should be protected and scrapers should be handy for frosty windshields.

On Wednesday morning, colder air will reach even farther south and east. There is potential for a frost as far south as northern portions of Illinois.

With chilly air moving across the very warm water of the northern Great Lakes, a few snow flakes could fly or mix in with rain showers around the Upper Peninsula of Michigan on Tuesday night. According to the National Oceanographic Data Center, water temperatures are still in the lower 60s in Lake Superior.

While no snow accumulations are expected, seeing snow flakes may catch some off-guard so early in the season.